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Digital signal processing


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  • 1. Technology Training that Digital Signal Processing
  • 2. Technology Training that Welcome to this webinar with Dr Steve Mackay There are at least 3 ways to interact with your presenter today. 1. Use the Text tab, near bottom left of your screen. Type the message in the space next to the “Send” button, then enter or click Send. (Ensure “All” is selected in the drop-down menu under the typing area) 2. Use the Emoticons selection in the text window – choose an emoticon then click send or enter. 3. Talk! Click the Push To Talk button. The button will change to yellow when you are queued, then green to show that your microphone is live. Remember to click it again when you have spoken This 45 minute session will commence shortly! RH
  • 3. Technology Training that Steve Mackay • Dean of Engineering • Worked for 30 years in Industrial Automation • 30 years experience in mining, oil and gas, electrical and manufacturing industries
  • 4. Technology Training that DSP • Digital - finite set of distinct values. • Analog - continuous range of values. • DSP Processing means processing of signals which are: – Discrete in time. – Discrete in amplitude.
  • 5. Technology Training that Two sources of discrete signals •Ones that are discrete in nature. •Sampled version of a continuous-time signal.
  • 6. Technology Training that Why Process Signals Digitally? • The signals are inherently discrete in nature. • Consistency -- compared with analog methods.
  • 7. Technology Training that Definition of Terms • Signals: A quantity that can be measured over time. • Frequency: A signal is said to have a frequency of 50 or 60 Hz. • Spectrum: Some signals have a combination of frequencies.
  • 8. Technology Training that • Low Pass Filter: This lets through the low pass component. • Bandpass Filter: Only a range of frequencies is passed through intact. • High-pass Filter: Allows frequencies above a certain frequency to pass through intact.
  • 9. Technology Training that Some Application Areas • Speech and Audio Processing. – Coding. – Synthesis. – Recognition.
  • 10. Technology Training that Companding Process
  • 11. Technology Training that Adaptive Differential Pulse Code Modulator
  • 12. Technology Training that Linear Predictive Coding
  • 13. Technology Training that Image and Video Processing • Image Enhancement. • Image Restoration. • Image Compression and Coding.
  • 14. Technology Training that Adaptive Filtering • Noise Cancellation. • Echo Cancellation. • Channel Equalisation.
  • 15. Technology Training that Adaptive Noise Cancellation System
  • 16. Technology Training that Adaptive Echo Cancellation System
  • 17. Technology Training that Adaptive Equalizer in Training Mode
  • 18. Technology Training that Control Applications • Controlling closed-loop feedback systems. • Controller implements algebraic algorithms such as filters and compensators.
  • 19. Technology Training that Digital Closed Loop Control System
  • 20. Technology Training that Sensor or Antenna Array Processing • Spatially distributed sensors are used for receiving signals from some sources. • Coherent summing of outputs from these sensors referred to as beamforming. • One can “listen” preferentially to wavefronts originating from one direction over another.
  • 21. Technology Training that Digital Communication • New Architecture called software radio. • Use of wideband A/D and D/A converters to convert RF or IF signals directly.
  • 22. Technology Training that Software Radio Architecture
  • 23. Technology Training that Converting Analog to Digital Signals and Vice Versa
  • 24. Technology Training that A Typical DSP System • Three stages: – The analog signal is digitized. This involves • sampling • quantization – Digital signal processed by DSP algorithms. – Outputs converted back into analog signals.
  • 25. Technology Training that Analog-Digital-Analog
  • 26. Technology Training that Temperature Variation in a Day
  • 27. Technology Training that The Sampling Process
  • 28. Technology Training that Uniform Sampling Theorem • If a continuous time signal contains no frequency components higher than W Hz, then it can be completely determined by uniform samples taken at a rate fs samples per second where • or, in terms of the sampling period f Ws ≥ 2 T W ≤ 1 2
  • 29. Technology Training that Two Bandlimited Spectra
  • 30. Technology Training that Replication of Spectrum through Sampling
  • 31. Technology Training that Replicated Spectrum
  • 32. Technology Training that Aliasing
  • 33. Technology Training that Sampling at Different Rates
  • 34. Technology Training that Effect of Aliasing
  • 35. Technology Training that Anti-aliasing Filters • Process the signal before it is sampled so they are always analog filters. • Usually low-pass filters unless bandpass sampling techniques are used.
  • 36. Technology Training that Analog-to-Digital Conversion with Anti-alias Filtering
  • 37. Technology Training that Implications of Non-ideal Anti-alias Filters • Sample at higher than Nyquist rate. • If sampling rate cannot be changed, then a filter with sharper cut-off (implying a higher order filter) has to be used.
  • 38. Technology Training that Limits on Sampling Rates • Practical choice of sampling rate is determined by two factors: – Sampling theorem places lower bound on the allowed values of sampling frequency. – Economics of hardware imposes upper bound on sampling frequency.
  • 39. Technology Training that Thank You For Your Interest If you are interested in further training, please visit: